**5. Front of organizations in fight (FOL) cooperatives: a case study**

In Argentina, after the political-economic crisis of 2001, movements of unemployed workers were formed, including the FOL. Within these movements labor cooperatives were developed. One of the activities performed in a cooperative way is horticulture, which is carried out in community gardens located within popular neighborhoods, many of them developed in poor settlements. The majority of the production of these gardens is destined to the neighborhood dining rooms; therefore they are an important component improving the diet of hundreds of families, who otherwise only ingest carbohydrates and canned food. In turn, these spaces serve as a reference for the entire neighborhood and encourage exchange and knowledge between neighbors. Therefore, self-sustaining neighborhoods are generated with less garbage, different exchange relationships, and healthier food. However, horticultural gardens located in these popular neighborhoods often have one main problem; they were developed on soils highly modified. Urban soils or "anthropic soils" have been disturbed profoundly by human activity through the mixing, importing and exporting of materials [64, 65], and they are often characterized by contamination, compaction and soil sealing, as well as deposition, and removal or mixing of natural substrates. Soils in the urban environment tend to be very disturbed because of surrounding human activities and might even be exogenous (i.e., transported from elsewhere) [66, 67]. Therefore, the properties of urban soils are normally not favorable for plant growth and their role in food production is compromised [68].

Soils from horticultural gardens developed in poor settlements from La Plata city, were sampled during 2018 and 2019. Site 1 corresponds to "Barrio Altos de San Lorenzo," which is located on an old landfill pit that has received the contribution of the surrounding stream, Site 2 and 3 are located in "Barrio el Carmen," built on top of material dragged from the bottom of the Maldonado stream (**Figure 9**).

The most outstanding characteristics of these soils were: moderate bulk density, high pH and low TOC content (**Table 4**).

These conditions necessarily involve the application of soil recovery management practices in the horticultural gardens. In this sense, agroecology proposes soil management strategies that can contribute to improve their productive properties. To guarantee the success of the popular gardens within the same organizations, workshops and training for agroecological production are given. The gardens are fertilized with compost that is obtained from compostable household waste. Moreover, crop rotation and crops associations are considered to improve nutrient balances and aromatic species that serve as insect repellents are sown. Agroecology takes advantage of the natural processes of interactions that occur in an horticultural field in order to reduce external inputs (many of them potential contaminants and toxic compounds) and improve biological efficiency of cropping systems [69].

The horticultural gardens managed by FOL cooperatives in the neighborhoods of "Altos de San Lorenzo" and "El Carmen," unlike what happens in peri-urban productions, are irrigated with water from the water supply network which is of better quality than the water pumped from wells (lower electrical conductivity and lower pH). However, given the precarious nature of these settlements, many of them are illegally occupying fiscal lands, do not have legal access to the water supply network and make unsafe connections that can become contaminated with faecal matter (**Table 5**).

**129**

improved (**Figure 10**).

**Figure 9.**

**Table 4.**

*Location of sampling sites.*

Altos de San Lorenzo

Ideal scenario Lower than

*values for adequate crop production [62].*

1.1

physical properties [69].

*Soil Quality Problems Associated with Horticulture in the Southern Urban and Peri-Urban Area…*

After 3 years of agroecological production in the neighborhoods under study,

El Carmen 1.28 8.70 1.14 30 28 52 Clay

3.5 *BD: bulk density by cylinder method [15]; Soil texture: clay, sand and silt percentage (USDA triangle); pH: pH in water 1.2.5 by potentiometry [17]; TOC: total oxidative carbon by Walkley and Black [18]. Ideal scenario: reference* 

5.5–7.0 Greater than

Although urban soils from the popular neighborhoods studied had electric conductivity levels below the risk thresholds for any crop, this property decreased in the horticultural gardens which could be related to salts washing as a result of irrigation with non-saline water (**Figure 10b**). No improvements were found regarding total N content (**Figure 10d**), this could be explained due to the use of vegetable compost as the only fertilizer. Composting from household waste usually has low N content and high C/N ratio [72], therefore a source of nitrogen should be considered to improve soil quality, for example through the incorporation of green manure with legumes which are able to fix atmospheric nitrogen or including more

Bulk density diminished and an increase in TOC was observed (**Figure 10c** and **f**), these improvements are linked to the use of compost as an organic amendment in the agroecological gardens [70, 71] which not only acts as fertilizer but also improves soil

soil sampling was performed and it was observed that some characteristics

*Urban soils characteristic in not cultivated sites: Altos de San Lorenzo y El Carmen.*

**Sites BD g cm<sup>−</sup><sup>3</sup> pH TOC % Texture**

**Sand %**

1.17 7.91 0.74 27 34 39 Clay

**Silt %**

**Clay % Soil** 

**texture**

loam

*DOI: http://dx.doi.org/10.5772/intechopen.90351*

*Soil Quality Problems Associated with Horticulture in the Southern Urban and Peri-Urban Area… DOI: http://dx.doi.org/10.5772/intechopen.90351*

**Figure 9.** *Location of sampling sites.*

*Urban Horticulture - Necessity of the Future*

food and nutritional security [60].

the urban environment, participatory governance, management of the territory and

In Argentina, after the political-economic crisis of 2001, movements of unemployed workers were formed, including the FOL. Within these movements labor cooperatives were developed. One of the activities performed in a cooperative way is horticulture, which is carried out in community gardens located within popular neighborhoods, many of them developed in poor settlements. The majority of the production of these gardens is destined to the neighborhood dining rooms; therefore they are an important component improving the diet of hundreds of families, who otherwise only ingest carbohydrates and canned food. In turn, these spaces serve as a reference for the entire neighborhood and encourage exchange and knowledge between neighbors. Therefore, self-sustaining neighborhoods are generated with less garbage, different exchange relationships, and healthier food. However, horticultural gardens located in these popular neighborhoods often have one main problem; they were developed on soils highly modified. Urban soils or "anthropic soils" have been disturbed profoundly by human activity through the mixing, importing and exporting of materials [64, 65], and they are often characterized by contamination, compaction and soil sealing, as well as deposition, and removal or mixing of natural substrates. Soils in the urban environment tend to be very disturbed because of surrounding human activities and might even be exogenous (i.e., transported from elsewhere) [66, 67]. Therefore, the properties of urban soils are normally not favorable for plant growth and their role in food production is compromised [68].

Soils from horticultural gardens developed in poor settlements from La Plata city, were sampled during 2018 and 2019. Site 1 corresponds to "Barrio Altos de San Lorenzo," which is located on an old landfill pit that has received the contribution of the surrounding stream, Site 2 and 3 are located in "Barrio el Carmen," built on top

The most outstanding characteristics of these soils were: moderate bulk density,

These conditions necessarily involve the application of soil recovery management practices in the horticultural gardens. In this sense, agroecology proposes soil management strategies that can contribute to improve their productive properties. To guarantee the success of the popular gardens within the same organizations, workshops and training for agroecological production are given. The gardens are fertilized with compost that is obtained from compostable household waste. Moreover, crop rotation and crops associations are considered to improve nutrient balances and aromatic species that serve as insect repellents are sown. Agroecology takes advantage of the natural processes of interactions that occur in an horticultural field in order to reduce external inputs (many of them potential contaminants and toxic compounds) and improve biological efficiency of cropping

The horticultural gardens managed by FOL cooperatives in the neighborhoods of "Altos de San Lorenzo" and "El Carmen," unlike what happens in peri-urban productions, are irrigated with water from the water supply network which is of better quality than the water pumped from wells (lower electrical conductivity and lower pH). However, given the precarious nature of these settlements, many of them are illegally occupying fiscal lands, do not have legal access to the water supply network and make unsafe connections that can become contaminated with faecal

of material dragged from the bottom of the Maldonado stream (**Figure 9**).

high pH and low TOC content (**Table 4**).

**5. Front of organizations in fight (FOL) cooperatives: a case study**

**128**

systems [69].

matter (**Table 5**).


*BD: bulk density by cylinder method [15]; Soil texture: clay, sand and silt percentage (USDA triangle); pH: pH in water 1.2.5 by potentiometry [17]; TOC: total oxidative carbon by Walkley and Black [18]. Ideal scenario: reference values for adequate crop production [62].*

#### **Table 4.**

*Urban soils characteristic in not cultivated sites: Altos de San Lorenzo y El Carmen.*

After 3 years of agroecological production in the neighborhoods under study, soil sampling was performed and it was observed that some characteristics improved (**Figure 10**).

Bulk density diminished and an increase in TOC was observed (**Figure 10c** and **f**), these improvements are linked to the use of compost as an organic amendment in the agroecological gardens [70, 71] which not only acts as fertilizer but also improves soil physical properties [69].

Although urban soils from the popular neighborhoods studied had electric conductivity levels below the risk thresholds for any crop, this property decreased in the horticultural gardens which could be related to salts washing as a result of irrigation with non-saline water (**Figure 10b**). No improvements were found regarding total N content (**Figure 10d**), this could be explained due to the use of vegetable compost as the only fertilizer. Composting from household waste usually has low N content and high C/N ratio [72], therefore a source of nitrogen should be considered to improve soil quality, for example through the incorporation of green manure with legumes which are able to fix atmospheric nitrogen or including more


*MAB: mesophylls aerobic bacteria; TC: total coliforms; E. coli: Escherichia coli; PA: Pseudomonas aeruginosa; +, presence; 0, absence; pH: pH in water 1.2.5 and EC: electrical conductivity in water 1.2.5 by potentiometry [17]. References levels for drinking water quality according to CAA [41]. \* of secondary importance according to CAA [41].*

#### **Table 5.**

*Irrigation water characteristics of urban sites.*

#### **Figure 10.**

*(a) pH: pH in water 1; 2.5 (potentiometry) [17]; (b) EC: electrical conductivity in water 1; 2.5 (potentiometry) [17]; (c) TOC: total organic carbon (Walkley and Black) [18]; (d) TN: total nitrogen (Kjeldahl); (e) EP: extractable phosphorus (Bray and Kurtz 1) [20] and (f) BD: bulk density [15] for NC: not cultivated sites and cultivated sites (C). Vertical bars indicating the standard deviation. Different letters show significant differences between treatments according to Tukey (p < 0.05) [32].*

legumes in crop rotation. Another property that could not be improved was pH (**Figure 10a**), which was expected, since pH is one of the chemical properties of the soil that varies the least, because it is an intrinsic characteristic of the soil genesis [73, 74]. To generate a significant change in pH, some specific corrective amendment should be applied, for example calcium sulfate.

With respect to extractable P [12, 34], reported that soils from this area, in their natural condition, are characterized by having low levels of extractable P (less than 10 mg kg<sup>−</sup><sup>1</sup> ). Other studies in the southern peri-urban area reported higher values, close to 20 mg kg<sup>−</sup><sup>1</sup> in uncultivated soils [13, 14]. In this study, we worked with urban

**131**

*Soil Quality Problems Associated with Horticulture in the Southern Urban and Peri-Urban Area…*

soils composed of material removed from the stream that receives runoff water from the entire basin. Phosphorus from many human activities, mainly the use of fertilizers and amendments in horticultural productions of the peri-urban area [8, 14, 26], could have been transported dissolved along with the runoff water and be retained in the clays [44] of the stream bed material that was subsequently used to build the urban soils of some settlements. This could be the reason why high levels of extractable P were found even in uncultivated soils from popular neighborhoods (**Figure 10e**). Although this section aims to show how urban land can be improved for food production, it is important to take into account some sanitary characteristics of the material on which food is grown, such as knowing the content of heavy metals

Horticultural soils from the green belt of Buenos Aires are showing alarming signs of physical, chemical and biological degradation as a consequence of inappropriate management practices applied since many decades ago. The most important processes associated with soil degradation in this area were salinization and alkalization principally as a consequence of irrigation with water with high levels of sodium bicarbonate and excessive application of organic amendments. The mentioned processes are also associated with nutritional imbalances and the loss of soil structure. Soil structure is also negatively affected by the loss of soil organic matter, usually observed in intensive agricultural systems as horticulture, which is not being compensated by organic amendments. On the contrary, the use of organic amendments and inorganic fertilizers indiscriminately, without performing the appropriate previous soil analyzes, or considering the needs of the crops, generates an over fertilization that increases the risks of nutritional deficiencies and could cause environmental damage due to nutrients leaching to underground water and superficial water courses. Particularly, there is a need for research on the dynamics of phosphorus since, although this element is considered immobile, the concentrations found in the soils of the area are so high that they could exceed the retention capacity of the soils and generate important environmental impacts at the basin level. Therefore, given the problems described in this chapter, it is necessary and urgent to change the productive paradigms if the intention is to ensure food production in the most important horticultural sector of the Argentine Republic. Soil is a non-renewable natural resource, its use and management must be integrated in a long-term perspective within a sustainable development approach; within a sustainable agriculture. Agroecology gives a new approach to the agricultural system, trying to provide solutions based on the interactions of physical, biological and socioeconomic components of the systems, integrating knowledge in the local and regional level to ensure sustainable production. Urban horticulture in Argentina is being developed mainly under an agro-ecological perspective. Although production within cities covers a much smaller area and of less economic importance than peri-urban horticulture, it is a role model, generating information from multiple local experiences that can serve as a basis to change large-scale horticultural production systems. The challenges that appear in urban production systems with an agro-ecological perspective are related, among other things, to the difficulties of producing in unnatural soils. In these soils, it is compulsory to perform quality analysis, treatment

and transformation to ensure a healthy and sustainable production.

other technological practices, and adequate soil management.

The search for agro-socioeconomical sustainability and new production system paradigms are the greatest challenges of modern agriculture, which involves among

*DOI: http://dx.doi.org/10.5772/intechopen.90351*

which are commonly raised in urban soils.

**6. Conclusions**

*Soil Quality Problems Associated with Horticulture in the Southern Urban and Peri-Urban Area… DOI: http://dx.doi.org/10.5772/intechopen.90351*

soils composed of material removed from the stream that receives runoff water from the entire basin. Phosphorus from many human activities, mainly the use of fertilizers and amendments in horticultural productions of the peri-urban area [8, 14, 26], could have been transported dissolved along with the runoff water and be retained in the clays [44] of the stream bed material that was subsequently used to build the urban soils of some settlements. This could be the reason why high levels of extractable P were found even in uncultivated soils from popular neighborhoods (**Figure 10e**).

Although this section aims to show how urban land can be improved for food production, it is important to take into account some sanitary characteristics of the material on which food is grown, such as knowing the content of heavy metals which are commonly raised in urban soils.
